A Reality Engine

From The Ego Tunnel: The Science of the Mind and the Myth of the Self by Thomas Metzinger:

The conscious brain is a biological machine—a reality engine—that purports to tell us what exists and what doesn’t. It is unsettling to discover that there are no colors out there is front of your eyes. The apricot-pink of the setting sun is not a property of the evening sky; it is a property of the internal model of the evening sky, a model created by your brain. The evening sky is colorless. The world is not inhabited by colored objects at all.

It is just as your physics teacher in high school told you: Out there, in front of your eyes, there is just an ocean of electromagnetic radiation, a wild and raging mixture of different wavelengths. Most of them are invisible to you and can never become part of your conscious model of reality. What is really happening is that the visual system in your brain is drilling a tunnel through this inconceivably rich physical environment and in the process is painting the tunnel walls in various shades of color. Phenomenal color. Appearance. For your conscious eyes only.

…Nor must your eyes be open to enjoy color experience. Obviously, you can also dream of an apricot-pink evening sky, or you can hallucinate one. Or you can enjoy an even more dramatic color experience under the influence of a hallucinogenic drug, while staring into the void behind your closed eyelids. Converging data from modern consciousness research show that what is common to all possible conscious sensations of apricot-pink is not so much the existence of an object “out there” as a highly specific pattern of activation in your brain. In principle, you could have this experience without eyes…

…it is not clear what counts as a whole experience: Are experiences discrete, countable entities? However, the flow of experience certainly exists, and cognitive neuroscience has shown that the process of conscious experience is just an idiosyncratic path through a physical reality so unimaginably complex and rich in information that it will always be hard to grasp just how reduced our subjective experience is. While we are drinking in all the colors, sounds, and smells—the diverse range of our emotions and sensory perceptions—it’s hard to believe that all of this is merely an internal shadow of something inconceivably richer. But it is.